Google will on Wednesday be accused by Brussels of illegally abusing its dominance of search in Europe, a step that ultimately could force it to change its business model fundamentally and pay hefty fines.

Margrethe Vestager, the EU’s competition commissioner, is to say that the US group will soon be served with a formal charge sheet alleging that it breached antitrust rules by diverting traffic from rivals to favour its own services, according to two people familiar with the case.

A decision on charges is to be taken by the college of 28 EU commissioners on Wednesday. Some commissioners are concerned that Ms Vestager has, according to one source, restructured and narrowed the case she inherited from her predecessor Joaquín Almunia. As well as search issues, the investigation has looked at allegations that Google illegally scrapes content from rivals, locks some publishers into using Google search ads, and makes it hard for advertisers to move campaigns to rival search engines.

Almost 20 complainants against Google want the search engine to abide by strict rules that ensure its formula treats its own services — providing results for travel, shopping and maps — no differently from rivals. Google and the commission declined to comment.

On top of the pressure from Brussels, this week Google is also under scrutiny in France where lawmakers are considering an initiative that would force it to hand over its secret formula for ranking websites.

Google supporters feel the commission’s volte-face on a settlement reflected politics rather than an independent assessment. No EU antitrust case has ever been extended to three settlement offers, or been revived after complainants were formally warned that their case was about to be rejected.

On top of the pressure from Brussels, this week Google is also under scrutiny in France where lawmakers are considering an initiative that would force it to hand over its secret formula for ranking websites.

The French senate is likely to adopt a bill this week which would allow the country’s national telecoms regulator to monitor search engines’ algorithms, with sweeping powers to ensure its results are fair and non-discriminatory.

If approved, the proposal would give Arcep, France’s telecoms regulator, powers to scrutinise any search engine that had sufficient power to “structure the functioning of the digital economy”. Google would be required to provide links to at least three rival search engines on its homepage, and disclose to users the “general principles of ranking”.

Requiring Google to disclose its algorithms is tantamount to requiring Google give away its trade secrets and patents for free.

Requiring Google to list other search engines is like requiring Ford dealerships to sell GM autos.